Methods and apparatus for pericardial access

ABSTRACT

An access tube is used for accessing an anatomic space, such as a pericardial space between the parietal and visceral pericardia. The access tube is advanced against the parietal pericardium and an anchor structure thereon embedded into the parietal pericardium. The access tube can then be used to separate the parietal and visceral pericardia and enlarge the pericardial space. After such enlargement, a needle or other access device can be introduced through the access tube into the pericardial space to provide access for a wide variety of purposes, including aspiration, infusion, and guidewire placement.

This application is a divisional of application Ser. No. 09/397,392,filed on Sep. 16, 1999, which issued as U.S. Pat. No. 6,423,051 on Jul.23, 2002.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to medical devices and methods.More particularly, the present invention relates to methods and devicesfor accessing the pericardial space in a minimally invasive manner.

The human heart is enveloped within a tissue structure referred to asthe pericardium. The pericardium includes two major portions. Theportion of the pericardium which lies immediately over the surface ofthe heart is referred to as the visceral pericardium. The second portionis formed as a sac around the visceral pericardium and is referred to asthe parietal pericardium. Normally, the visceral and parietal pericardialie in close contact with each other and are separated only by a thinlayer pericardial fluid. The space (really more of a potential space)between the visceral and parietal pericardia is referred to as thepericardial space.

Access to the pericardial space can be necessary or beneficial under avariety of circumstances. Open surgical access can be obtained via opensternotomy where the patient's sternum is divided and the parietalpericardium exposed. Alternatively, the pericardial space can beapproached from a skin incision made below the xiphoid through which theparietal pericardium is identified. Such approaches, however, are highlytraumatic, requiring general anesthesia and useful only under compellingcircumstances. Access to the pericardial space can also be achievedusing a thoracoscopic approach. Under general anesthesia, the left lungis deflated after which multiple holes are made for the thoracoscope andvarious instruments. The pericardium is then entered using standardvideoscopic techniques. The thoracoscopic approach typically requiresthe placement of a chest tube and admission to the hospital for theinitial 1-2 post-operative days.

In patients who require drainage of a large pericardial effusion, asimple percutaneous approach can be used. Through a small (2-4 mm)cutaneous incision between the xiphoid and costal cartilage, a spinalneedle (18-20 gauge) is advanced in a superior/posterior fashion. Atappropriate intervals, the stylet is removed and fluid aspiration isattempted. If no fluid is obtained, the stylet is replaced and theneedle advanced again. This cycle is repeated until fluid is aspirated.If the needle is advanced too far, the heart can be punctured and is whya large pericardial effusion must be present on ensure adequateseparation of the visceral-and parietal pericardia.

A minimally invasive method for accessing the pericardial space isdescribed in U.S. Pat. No. 5,827,216 to Igo et al. A pericardiocentesisapparatus is introduced via a subxiphoid approach to the heart. A vacuumis applied at a distal end of the device to form a “bleb,” i.e., alocally expanded region in the pericardium. A needle can then bepenetrated through the bleb, and the needle used for drawing fluids,delivering drugs, or the like. Although theoretically plausible, theability to reliably maintain a seal against the pericardium can beproblematic.

For these reasons, it would be desirable to provide additional andimproved methods and apparatus for the minimally invasive access to apatient's pericardial space. The methods and devices should be suitablefor a wide variety of minimally invasive approaches to the pericardium,including at least intercostal/transthoracic and subxiphoid approaches,and the like. The methods and devices should further provide for secureand stable capture of the parietal pericardium and permit the opening ofa large space or volume between the parietal and visceral pericardia.Such access methods and apparatus should be useful for a wide variety ofprocedures to be performed in the pericardial space, including fluidwithdrawal, drug delivery, diagnostic and therapeutic electrophysiologyprocedures, pacemaker lead implantation, defibrillator lead placement,transmysocardial revascularization, transmysocardial revascularizationwith drug delivery, placement of the left ventricular assist devices,placement of the arterial bypass graphs, in situ bypass, i.e., coronaryartery-venous fistulae, placement of drug delivery depots, closure ofthe left arterial appendage, and the like. At least some of theseobjectives will be met by the invention described herein.

2. Description of the Background Art

U.S. Pat. No. 5,827,216, describes a pericardial access tube which drawsa vacuum on the parietal pericardium as part of an access procedure, asdiscussed above. U.S. Pat. No. 5,071,428, describes a method foraccessing the pericardial space for defibrillation lead implantation bygrasping the parietal pericardium with forceps and cutting thepericardium with a scalpel. U.S. Pat. No. 4,281,659, describes a probesystem having paired helical wires for securing the probe to a patient'sskin. U.S. Pat. No. 4,164,943, describes a catheter anchor havingmultiple helical wires for securing the anchor to a patient's skin. U.S.Pat. No. 5,226,890, describes a trocar cannula anchor having a taperedthread for placement in a percutaneous tissue penetration. U.S. Pat. No.5,332,398, describes and intramedullary catheter having a threaded endfor implantation into a bone.

SUMMARY OF THE INVENTION

The present invention provides methods, apparatus, and kits foraccessing an anatomic space having a wall with an outer surface. Thewall may consist of a membrane, a capsule or the adventia, muscularisand endothelial layers of a hollow organ or vessel. The methods,apparatus, and kits are particularly useful for minimally invasiveaccess procedures, but could also be used for accessing internalanatomic spaces where initial access to the wall of the outer surfacesachieved via open surgical or other techniques. The present inventionwill be particularly useful for accessing a patient's pericardial spacefor performing a wide variety of procedures, generally as set forthabove.

The phrase “anatomic space” is meant to include any natural, potential,or created space or cavity within a patient's body where it may bedesirable to gain access for surgical, diagnostic, therapeutic, or anyother purpose. Usually, the anatomic space will be within an organ orstructure located beneath the patient's skin, such as the pericardialspace which lies between the visceral and parietal pericardia, both ofwhich lie beneath the chest wall and rib cage. Other internal organswhich may be accessed include the intestines, fallopian tubes, gallbladder, kidneys, and the like.

Methods according to the present invention for accessing an anatomicspace having a wall with an outer surface comprise embedding a distalend of an access tube into the outer surface. An access device, such asa stylet, needle, or other piercing instrument, may then be introducedthrough the access tube, penetrating the wall, and into the anatomicspace while the access tube stabilizes the wall. Embedding the distalend of the access tube can be achieved in a wide variety of ways.Typically, an anchor structure at the distal end is engaged against theouter surface of the anatomic space wall and subsequently penetratedinto the surface. For example, the anchor structure may comprise one ormore penetrating points which are embedded into the wall by rotation ofthe access tube, distal advancement of the access tube, or the like.While the penetrating points will typically be fixed on the access tube,it will also be possible to provide spring-loaded or other selectivelydeployable penetrating points which can be embedded into the anatomicspace wall while the access tube is held stationary. After the distalend of the access tube has been embedded into the anatomic space wall,the wall will usually be drawn or otherwise manipulated increasing theavailable access volume therein. In particular, by increasing theavailable volume, the risk of accidental injury from advancement of theaccess device into deep structures is significantly reduced. Increasingthe access volume, however, can have other benefits. For example, it canimprove the ability to image the anatomic space using a fiberopticimaging scope, permit the introduction of various devices, drug deliverystructures, or the like.

In preferred aspects of the present invention, the access device will bea hollow needle or stylet, and a guidewire will be positioned throughthe needle and into the anatomic space. The needle can then bewithdrawn, and the guidewire used for access of a variety of diagnostic,therapeutic, or other catheters and devices.

In a further aspect of the method of the present invention, apericardial space between the visceral and parietal pericardiums isaccessed by percutaneously positioning a distal end of an access tubeover the parietal pericardium. Positioning can be achieved either by atransthoracic or a subxiphoid approach beneath the sternum or from theabdominal cavity through the diaphragm, or the like. Once in position, adistal end of the access tube is embedded into the parietal pericardiumin a manner which does not engage the visceral pericardium. The accesstube is then drawn or otherwise manipulated to separate the parietalpericardium from the visceral pericardium to enlarge the availablevolume of the pericardial space therebetween. An access device, againusually a needle or hollow stylet, is then advanced through the accesstube penetrating the parietal pericardium entering the pericardialspace. Guidewires may then be positioned and a variety of particularprotocols performed, generally as listed above.

The present invention still further provides systems comprising anaccess tube and a needle, stylet, or other equivalent device. The accesstube has a distal end which can be selectively embedded into tissue, andthe needle, stylet, or other access device has a lumen which is usefulfor subsequent placement of a guidewire, as generally described above.Optionally, the system may further comprise the guidewire capable ofbeing positioned in the anatomic space through the needle.

The present invention still further provides kits for accessing thepericardial space of a patient. The kits comprise an access tube havinga distal end which can be selectively embedded into tissue. Exemplaryaccess tubes are described above. Kits will further compriseinstructions for use according to any of the methods set forth above.Kits may optionally further comprise a package for holding at least theaccess tube and usually the instructions for use. Exemplary packagesinclude boxes, trays, pouches, tubes, and the like. Usually, at leastthe access tube will be maintained sterilely within the package.Optionally, the needle, stylet, or other access device, may be included.Further optionally, the guidewires used for the methods of the presentinvention may also be included within the kit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a system according to the present inventioncomprising an access tube and an access device in the form of a needleor stylet.

FIG. 2 is an enlarged view of the distal end of the access tube of FIG.1.

FIGS. 3 and 4 illustrate an alternative construction of the access tubeof the present invention.

FIGS. 5A-5F illustrate use of the system of FIG. 1 for accessing apericardial space according to the method of the present invention.

FIG. 6 illustrates a further alternative access tube useful in themethods of the present invention.

FIG. 7 illustrates use of the access tube of FIG. 6 in accessing apericardial space according to the methods of the present invention.

FIG. 8 illustrates a kit constructed in accordance with the principlesof the present invention.

DESCRIPTION OF THE SPECIFIC EMBODIMENTS

Systems according to the present invention include an access tube and anaccess device. The access tube engages and captures an outer surface ofa wall which forms or surrounds the target anatomic space. In theexemplary case, the wall is the parietal pericardium which overlies thepericardial space over a patient's heart. The access device, in turn, isintended to pass through the access tube and to penetrate through theanatomic space wall and into the interior volume of the anatomic space.Using the access tube to first capture and stabilize the wall of theanatomic space facilitates introduction of the access device through thewall.

The access tube may have a wide variety of specific structures, but willgenerally be elongate, typically having a length in the range from 10 cmto 30 cm, more usually from 18 cm to 24 cm, and a relatively narrowmaximum width, usually having a diameter in the range from 3 mm to 20mm, more usually from 4 mm to 10 mm, and will have an anchor structureat its distal end in order to selectively engage and capture the outersurface of the anatomic space wall. The access tube allows forintroduction of the access device through the target region of theanatomic space wall which is being held by the access tube. Most simply,the access tube is a tubular or cylindrical structure (usually but notnecessarily having a continuous side wall without perforations) with theanchor structure disposed over a distal end thereof. Thus, the accessdevice may simply be introduced through the central lumen or passage ofthe access tube so that it passes out through the anchor structure atthe distal end of the device. Thus, when the anchor structure isengaging tissue, the access tube will necessarily pass through thatregion of tissue which is being held and stabilized by the distal end ofthe access tube. The ability to provide such peripheral engagement andstabilization of the anatomic space wall while the access tube is passedtherethrough is a particular advantage of the present invention.

The access device may also have a wide variety of specific forms, butwill usually be in the form of a needle, stylet, or other elongatestructure having a sharpened distal tip for passage through the tissueof the anatomic space wall. Usually, the access device will also have acentral lumen to permit introduction of a guidewire, infusion oraspiration of fluids, placement of leads or other implantable devices,or the like. Placement of a guidewire within the anatomic space mayfurther provide for introduction of a wide variety of other diagnosticand therapeutic catheters and devices. The access device will typicallybe longer than the access tube so that it may be passed therethrough,usually having a length in the range from 12 cm to 35 cm, more usuallyfrom 20 cm to 26 cm. The maximum width or diameter of the access devicewill permit its introduction through the access tube, usually being therange from 0.2 mm to 2.0 mm, preferably from 0.4 mm to 0.8 mm.

The exemplary access tube and access device described below arerelatively simple in construction. It will be appreciated that theconstruction could be varied in a number of ways for a variety ofpurposes. For example, the tubular structures of the access tube and/orthe access device could be non-linear, telescoping, perforated, or havemany other configurations. Additional features, such as additionallumens, imaging capabilities, pneumostatic valves, and the like, couldalso be added within the scope of the present invention.

Referring now to FIGS. 1 and 2, a first exemplary anatomic space accesssystem 10 according to the present invention will be described. Thissystem is particularly intended for access to a pericardial space, aswill be described in more detail below. System 10 comprises an accesstube 12 and an access device 14 in the form of a hollow needle or stylethaving a sharpened distal end 16. The access tube 12 comprises a tubularbody having a proximal end 18 and a distal end 20. The distal end 20 issimply an open port 22 having an annular surface 24. A plurality oftissue-penetrating elements 30 are disposed about the annular surface 24and are oriented so that they may be engaged against a tissue surfaceand penetrated into that surface by rotation of the access tube 12 aboutits central access. The dimensions of the access tube 12 and accessdevice 14 are generally within the ranges set forth above, and thetissue-penetrating elements will typically have a length (measuredaxially from the annular surface 24) in the range from about 0.5 mm to3.0 mm, and will further be oriented at an angle in the range from 5° to60° so that they penetrate into tissue as the tube 12 is rotated aboutits central axis.

The access tube 12 of FIGS. 1 and 2 is fabricated by attaching separatetissue-penetrating elements 30, typically short conical or horn-shapedneedles, to the annular surface 24 of the body of the access tube. Formass production, it may be desirable to more simply form thetissue-penetrating elements at the distal end of the access tube. Asillustrated in FIGS. 3 and 4, an access tube 40 having three penetratingelements 42 at its distal end may be formed from a flat sheet ofmaterial, typically metal, by forming the elements 42 into the flatsheet prior to rolling the sheet to form the tube. For metals, theelements may be formed by cutting, etching, abrasion, or anyconventional metal-working technique. The flat sheet may be rolled andthen closed over the mating longitudinal edges, typically by welding, orother conventional techniques.

Referring to FIGS. 5A-5F, use of the access tube 12 and access device 14for accessing a pericardial space PS of a patient will be described. Thepericardial space PS is formed between the visceral pericardium VP andthe parietal pericardium PP, as seen in FIG. 5A. The distal end of theaccess tube 12 can be introduced over the surface of the parietalpericardium PP, typically via a subxiphoid approach. After reaching theparietal pericardial surface, penetrating elements 30 may be engagedagainst the parietal pericardium and embedded therein by rotating theaccess tube 12 about its central axis, as illustrated in FIG. 5B. Thepenetrating elements 30 engage the parietal pericardium, but do notengage or advance into the visceral pericardium or structures below.Thus, once engaged, the access tube 12 is able to draw the parietalpericardium away from the visceral pericardium to create an enlargedpericardial space PS′, as shown in FIG. 5C. After drawing the parietalpericardium PP, the access device 14 may be introduced through theaccess tube 12 and into the enlarged pericardial space PS′, as shown inFIG. 5D. The access device 14 is then available to perform a widevariety of tasks and protocols. For example, it could be used forinfusion or aspiration of fluids, drug delivery, diagnostic andtherapeutic electrophysiology procedures, pacemaker lead implantation,defibrillator lead placement, transmysocardial revascularization,transmysocardial revascularization with drug delivery, placement of leftventricular assist devices, placement of arterial bypass graphs, in situbypass, i.e., coronary artery-venous fistulae, placement of drugdelivery depots, closure of the left atrial appendage, or the like.

In the exemplary embodiment of the present invention, the access device14 will be used to introduce a guidewire 40 into the enlargedpericardial space PS′, as shown in FIG. 5E. Once the guidewire 40 is inplace, the access device 14 may be withdrawn, leaving the guidewirepassing through the access tube 12, as illustrated in FIG. 5F. Theguidewire 40 may then be used to introduce a wide variety of cathetersor other diagnostic or therapeutic devices in order to perform any ofthe procedures listed above. In a preferred use, the guidewire 40 willbe used to introduce a catheter and related instruments for closing theleft atrial appendage, as generally described in copending applicationSer. No. 09/315,601, the full disclosure of which is incorporated hereinby reference.

The system of FIGS. 1 and 2 is particularly useful for engaging outersurface of the anatomic space walls in a generally perpendiculardirection, allowing the penetrating elements to engage and capture theunderlying tissue. In some instances, it may be desirable to providesystems intended to approach a tissue surface in a non-perpendiculardirection. As illustrated in FIG. 6, an access tube 50 can be providedwith a cylindrical body and an angled or chamfered distal end 52. Anannular surface 54 at the distal end 52 can be provided with a pluralityof fixed, generally axially aligned penetrating elements 56. Suchelements will be able to engage tissue as the access tube 50 is advancedin a distal direction, allowing the tissue surface to be captured atoblique angles.

As illustrated in FIG. 7, the access tube 50 can be used to access apericardial space PS from a subxiphoid approach. A patient's heart Hunderlies the sternum S beneath the chest wall CW, as illustrated inFIG. 7. The access tube 50 can be introduced beneath the inferior end ofthe sternum S to approach the parietal pericardium PP. The penetratingelements 56 can thus engage the parietal pericardium and draw it awayfrom the visceral pericardium VP. The access device 14 can then beintroduced through the access tube 50 and into the enlarged pericardialspace PS′. The access device 14 can be used for introducing a guidewireor any of the other purposed described above.

Referring now to FIG. 8, a kit 70 according to the present inventioncomprises at least an access tube (illustrated as access tube 12) andinstructions for use (IFU) setting forth a method according to thepresent invention for accessing an anatomic space. Optionally, the kitmay further include an access device, such as access device 14 describedabove, as well as packaging, typically in the form of a box, pouch,tray, tube, or the like. The kit 70 could further include a guidewireand other components or instruments useful for positioning the accesstube and access device in performing the access methods. Instructionsfor use will usually be printed on a separate sheet of paper in the formof a package insert, but could also be printed partly or wholly on thepackaging itself.

While the above is a complete description of the preferred embodimentsof the invention, various alternatives, modifications, and equivalentsmay be used. Therefore, the above description should not be taken aslimiting the scope of the invention which is defined by the appendedclaims.

What is claimed is:
 1. A system for accessing an anatomic space having awall, said system comprising: an access tube having a distal end whichcan be selectively engaged at an outer side of the wall; a penetratingstructure disposed at the distal end of the access tube, the penetratingstructure which can penetrate the outer side of the wall and through aninner side of wall, the penetrating structure can engage the inner sideof the wall, such that proximal movement of the distal end of the accesstube causes corresponding enlargement of the anatomic space; and aneedle having a lumen therethrough, said needle being configured to passthrough the access tube and penetrate into the anatomic space when theaccess tube is engaged with the outer side of the wall of the anatomicspace and when the penetrating structure is engaged with the inner sideof the wall of the anatomic space.
 2. A system as in claim 1, whereinthe penetrating structure comprises an anchor structure at the distalend of the access tube.
 3. A system as in claim 2, wherein the anchorstructure comprises one or more penetrating points.
 4. A system as inclaim 3, wherein the penetrating points are inclined so that theypenetrate into tissue when the access tube is rotated about its longaxis.
 5. A system as in claim 1, further comprising a guidewireconfigured to be positioned into the anatomic space through the needle.6. A kit for accessing the pericardial space between the visceral andparietal pericardium, said kit comprising: an access tube having adistal end which can be selectively engaged at an outer side of theparietal pericardium; a penetrating structure disposed at the distal endof the access tube, the penetrating structure which can penetrate theouter side of the parietal pericardium and through an inner side of theparietal pericardium, the penetrating structure can engage the innerside of the parietal pericardium; and instructions for use setting fortha method for accessing an anatomic space having a wall, said methodcomprising: engaging a distal end of an access tube to an outer side ofthe wall; embedding a penetrating structure disposed at the distal endof the access tube into the outer side of the wall and through an innerside of the wall; drawing the access tube proximally to raise the wallover the anatomic space and to enlarge the anatomic space; andintroducing an access device through the access tube, penetrating thewall and into the anatomic space while the access tube stabilizes thewall.
 7. A system as in claim 1, wherein the penetrating structure isengaged with the inner side of the wall so as to be engaged underneaththe wall.
 8. A system for accessing the pericardial space between thevisceral and parietal pericardium, said system comprising: an accesstube having a distal end which can be selectively engaged at an outerside of the parietal pericardium; a penetrating structure disposed atthe distal end of the access tube, the penetrating structure which canpenetrate the outer side of the parietal pericardium and through aninner side of the parietal pericardium, the penetrating structure canengage the inner side of the parietal pericardium, such that proximalmovement of the distal end of the access tube causes correspondingenlargement of the anatomic space; and a needle having a lumentherethrough, said needle being configured to pass through the accesstube and penetrate into the pericardial space when the access tube isengaged with the outer side of the parietal pericardium and when thepenetrating structure is engaged with the inner side of the parietalpericardium.